Michael addition of chiral formaldehyde N,N-dialkylhydrazones to activated cyclic alkenes

The nucleophilic conjugate addition of chiral formaldehyde N,N-dialkylhydrazones to doubly activated cyclic alkenes proceeds smoothly to afford the corresponding Michael adducts , , , , , , and in variable yields and selectivities. The reactions take place either spontaneously or in the presence of MgI2 as a mild Lewis acid depending on the type of substrate. Release of the chiral auxiliary was achieved by transformation of the hydrazone moiety into acetals, dithioacetals or nitriles.